1. Field of the Invention
The present invention relates to improvements in electric fencing monitoring systems, particularly for multiple fence arrangements of relatively long lengths.
2. Description of Prior and Related Art
Electric fences utilizing an energizer at one end for producing a pulse along the length of the fence have been known for many years and are presently being used more frequently due to a more general awareness of their advantages over conventional fences. The pulse generated is of such a level and frequency that it will deter passage of animals and the like through the fence. The advantages of electric fences are particularly significant in farm fencing arrangements where temporary paddocks are desired and electric fences are becoming more extensively used for this purpose.
Electric fences permit a simpler, lighter and therefore cheaper construction than conventional fences as there is no longer any need to make design allowances for animals endeavouring to push through the fence to get to pastures on the other side.
However, problems do arise if a power loss of a certain dimension, or a complete power loss occurs along the fence; because of the light construction of the fence stock losses through the fence can occur or damage to crops can result from intrusion of ones own stock or foreign animals into crop growing areas. Therefore there is a need for some means of simply determining when a fault occurs along a conductor of a sufficiently significant nature to make the conductor ineffective for its design purpose and when such fault occurs an alarm is raised.
Some proposals have been made for alarm systems for these types of fences, however, these have generally been complex or ineffective in operation, particularly for fences of considerable length. An electric fence system suitable for lengthy systems has been proposed by us as described in our published Australian patent application No. 509,325. This system operates with a monitoring device including an alarm and a reflector means in the fence which reflects pulse signals to the monitoring device which will activate the alarm if the pulses are absent or are weak. This system has been used in the field and found to work satisfactorily. The present invention aims to remove the need for providing a reflector device in an electric fence alarm system and yet operates effectively.